Parker-Hannifin Corporation

William Power

Xingen Dong

Robert E Oehman, Jr

Improvements in trunnion shaft-controlled swashplate axial hydraulic piston pumps as well as hydraulic systems used in hydrostatic transmissions utilized. e.g., in zero-turn-radius (ZTR) wheeled vehicles, such as grass mowers, with one embodiment thereof pertaining to, in combination, the noted pump, devoid of any internal servo control, and a reversible power actuator, for controlling the angle of the swashplate, externally affixed to the housing containing the pump and operatively interconnected with an end of the trunnion shaft extending from the pump housing, with the power actuator being one of a rotary actuator, a fluid power axial cylinder and a rotary electronic actuator. Usage in a ZTR wheeled vehicle requires the prime mover to independently drive two hydraulic transmissions that are controlled by a human operator via a mechanical lever, either two single-axis or one dual-axis joystick control, or a steer-by-wire unit, connected with right and left power actuators

Control devices for swashplate type variable displacement piston pump

A fluid transfer machine includes a positive displacement, rotary-type pumping mechanism driven by a drive shaft. The drive shaft is lubricated and cooled by locating the drive shaft in a primary flow path in the machine. Fluid is directed from the inlet through a passage that intersects a cavity surrounding the drive shaft, at a location between a pair of journal bearings. The fluid then continues directly to the suction side of the pumping mechanism. The drive shaft could also be located on the pressure side of the pumping mechanism. The primary flow cools and lubricates the drive shaft and drive shaft bearings, and reduces the size and complexity of the machine, as additional cooling and lubrication flow passage(s) are not required.

Fluid transfer machine with drive shaft lubrication and cooling

A test device and a process for determining the accuracy of positive displacement gear pumps includes hydraulic cylinders which are fluidly connected to the output fluid flow(s) from a test pump. Each outlet flow is directed to a separate hydraulic cylinder. The test pump is driven by a motor for a preset number of revolutions. The length of stroke of the piston in each hydraulic cylinder is then determined, which corresponds to the volume of fluid provided from each pump outlet during the revolution of the gears in the pump. It can then be determined if the volumetric accuracy and efficiency of the pump is within acceptable limits.

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Greeneville, TN, United States of America

William Power